AB1358 AN OLD METHOD FOR CURRENT CHALLENGES: SKIN TEST CONVERSION OF PURIFIED PROTEIN DERIVATIVE (PPD) IN RHEUMATOLOGICAL PATIENTS TREATED WITH ANTI-TNF-α
Authors: B. Abdala, A. Ringer, J. Ruffino, F. Martinez, M. C. Argento, S. Chulibert, D. Carbone, F. Lucci, A. Gatica, L. Cichillitti, M. Palatnik, M. N. Cortese, J. C. Crema, M. Lagrutta, B. Finucci Curi, A. Co, M. Abdala
Journal: Annals of the Rheumatic Diseases (2022)

Background Anti-TNF-α are a cornerstone for the treatment of multiple rheumatic diseases. They are associated with an increased risk of developing tuberculosis (TB), which is endemic in several countries and an important burden across the globe. Purified protein derivative (PPD) is one of the tests used to demonstrate a latent TB infection (LTBI). Screening is recommended for TB prior to the onset of anti-TNF-α and monitoring evaluating possible conversion of PPD during treatment, defined as the change from a negative (&lt;5 mm) to positive result (≥5 mm). Identification and treatment of LTBI can reduce the risk of disease development by up to 90%. Currently the results of PPD conversion and its interpretation during anti-TNF-α treatment are variable and that is why we set out to know the frequency of conversion of PPD in this group of patients in our environment. Objectives To identify PPD conversion in patients with rheumatological diseases undergoing anti-TNF-α treatment. Methods A descriptive, analytical, observational, retrospective study was conducted from January 1, 2018 to January 1, 2022. Inclusion criteria: Patients &gt;18 years old, diagnosed with rheumatological diseases and treated with anti-TNF-α for more than 3 consecutive months, with a negative PPD (&lt;5 mm diameter) previous starting anti-TNF-α and a normal chest X-ray. Results 62 patients (age 45.8 ± 12.5 years), with rheumatological diseases (41 rheumatoid arthritis, 7 juvenile idiopathic arthritis, 5 ankylosing spondylitis, 4 psoriatic arthritis, 4 uveitis and 1 interstitial keratitis) under anti-TNF-α therapy (35 adalimumab, 18 certolizumab, 9 etanercept) were included. Concomitant use of immunomodulators (52 methotrexate, 23 leflunomide, 10 hidroxicloroquine, 3 sulfasalazine, 2 azathioprine and 1 mycophenolate mofetil) and glucocorticoids (33/62) was observed. The conversion of PPD took place in 4 patients (6.5%) (Table 1). Table 1. “Patient’s characteristics” Sex Age RD anti-TNF-α Time doing anti-TNF-α DMARD GCS PPD Chest X-ray TB prophylaxis 1 Male 66 PsA adalimumab 6 years methotrexate No 5 mm Normal Isoniazid 2 Female 56 RA adalimumab 10 years methotrexate No 5 mm Normal Isoniazid 3 Female 62 RA adalimumab 5 years methotrexate Yes 10 mm Normal Isoniazid 4 Male 45 AS certolizumab 1 year No No 20 mm Normal Isoniazid AS, ankylosing spondylitis; DMARD, disease-modifying antirheumatic drugs; GCS, glucocorticosteroids; PPD, purified protein derivative; PsA, psoriatic arthritis; RA, rheumatoid arthritis; RD, rheumatological disease; TB, tuberculosis. Conclusion Considering the prevalence of TB in our country, this research showed a lower PPD conversion percentage compared to previous reports. Anti-TNF-α have radically changed the evolution of rheumatological diseases, considerably improving the patient’s quality of life. With the increase in the accessibility of anti-TNF-α worldwide, new challenges have arisen regarding infectious diseases such as TB, which is endemic in some countries. PPD is a well known, cheap, sensitive and widely available method, suitable for LTBI diagnosis. Although sensitivity could be increased using, in addition, other LTBI detection methods such as IGRAs (interferon gamma release assays), they are usually unavailable in developing countries (1-3). References [1]Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clin Infect Dis 2017; 64(2):e1-e33. [2]Cerda O, Correa M, Granel A, Marcos A, Giraldo C, Rillo O et al. Tuberculin test conversion in patients with chronic inflammatory arthritis receiving biological therapy. European Journal of Rheumatology. 2019;6(1):19-22 [3]Busquets-Pérez N, Ponce A, Ortiz-Santamaria V, de Agustín de Oro J, Hernández-Rico Y, Vidal I et al. How many patients with rheumatic diseases and TNF inhibitors treatment have latent tuberculosis? 2020; 13(5):282-286. Disclosure of Interests None declared